Project

Discipline

breastfeeding; infant; rhinitis; asthma; atopy; cohort; wheeze; lung function; paediatrics; epidemiology

Lead
Lay summary
Breathing problems, particularly respiratory infections and allergic disorders, are important health problem in childhood and a major cause of visits to the general practitioner and hospital stays. Thus, they contribute significantly to health care costs. Breastfeeding has many benefits for maternal and child health. Whether it has also beneficial effects on lung growth, respiratory infections and the development of allergic disorders is insufficiently understood. The objectives of this research project are: (i) To study whether breastfeeding affects  lung growth and function, analyzing data from three independent longitudinal (cohort)  studies; (ii) to investigate whether breastfeeding influences the occurrence of respiratory disease  during the first year of life, using weekly data on respiratory symptoms and infections; (iii) to investigate the intermediate pathways (early infections, allergy) through which breastfeeding affects respiratory outcomes (asthma, hayfever, lung function) at school age, using a statistical method called path analysis. We believe that this project will add significantly to the current knowledge of effects of breastfeeding on respiratory illness and lung development in children. In view of the high relevance of breastfeeding for public health and the rising asthma prevalence in many countries our results will be likely to inform policy.

Direct link to Lay Summary

Last update: 21.02.2013

Active participation

Number	Title	Start	Funding scheme

Background: There is an ongoing debate about whether and how breastfeeding (BF) affects lung growth, the risk of upper and lower respiratory infections and the development of atopic disorders including allergic rhinitis and asthma. Results from previous studies are heterogeneous, differ by disease phenotype and age when respiratory outcomes were assessed and suggest effect modification by maternal atopy. The primary and secondary research performed in the last grant period produced exciting results, which now need to be validated in independent datasets and for which potential causal pathways need to be identified, for example the role of upper and lower respiratory infections and atopy. Our analyses of lung function data from the Leicester 1998 cohort found that spirometric lung function at school age was better in breastfed children, particularly those with asthmatic mothers (Dogaru AJRCCM 2012, doi 10.1164/rccm.201108-1490OC). We then complemented lung function measurements by plethysmography and 3He magnetic resonance, a novel method to estimate alveolar dimensions (Narayanan AJRCCM 2012;185:186-91). Again, breastfed children tended to have increased lung volumes, higher flows and larger alveolar dimensions, particularly if their mothers had asthma (manuscript in preparation). Finally, in a systematic review and meta-analysis of 38 cohort studies from developed countries we found a protective effect of BF on development of asthma and wheeze in early life that diminished with age. Objectives: The proposed project will expand the previous work. In particular, we will: (i) test the robustness of our findings on BF and lung function in three independent cohorts and extend these analyses to lung growth; (ii) investigate associations between BF and respiratory outcomes in infancy, using weekly data on symptoms, infections and respiratory rate; (iii) investigate pathways (early infections, atopy) between BF and respiratory outcomes (asthma, allergic rhinitis, lung function) at school age, using a path analysis, that accounts for direct and mediated effects and their temporal sequence.Methods: In Part i) We will analyse the association between BF and lung function in three independent childhood cohorts (Leicester 1990, N=480; German Multicentre Allergy Study [MAS], N=650; and Avon Longitudinal Study on Parents and Children [ALSPAC], N=7000). We will also look at changes in lung function between age 5 weeks and 6 years using repeated lung function data from the Bern Infant Lung Development (BILD) cohort (N=250). In Part ii) We will analyse prospectively assessed weekly data on BF and respiratory outcomes (symptoms, infection, respiratory rate) in infancy from the BILD cohort (N=450). In Part iii) Using a path analysis of repeated measurements from the Leicester 1998 cohort (N=4000), we will simultaneously model asthma and allergic rhinitis at age 9-13 years and intermediate outcomes at younger ages. This analysis allows the temporal sequence to be investigated and the direct effects of BF and indirect effects mediated through infections and atopy to be distinguished. In a subsample we will apply the same model to lung function and skin prick test response at age 9-13 years (N=1500). Output and significance: We believe that this project will add significantly to the current knowledge of effects of BF on respiratory morbidity and lung development in children. Importantly, we will use a standardised approach to analysis, describe changing effect sizes with increasing age and avoid or minimise methodological pitfalls of earlier studies. The detailed information on respiratory infections and atopy in our cohort datasets will allow causal pathways to be explored and hypotheses regarding potential mechanisms to be generated. Our study is topical in view of the high public health relevance of BF and the rising asthma prevalence in many countries, and results will be likely to inform policy.